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Owls among us in the dark of night

I remember on a moonlit December night many years ago, while snowshoeing in the powder snow through a favorite woodland of mine, frequently stopping to rest and listen, the sensation of frigid air stinging my nose and filling my lungs with its invigorating coolness.

Surrounded by leafless trees, popping occasionally in seeming opposition of the bitter cold, I marveled as ominous trunks and branches cast long dark shadows across the white blanket spread below. I delighted in the experience of wintertime's snowy solitude.

The only sign of life, save from my own vaporized breath hanging like a cloud about my head, was a well-used deer trail full of tracks and droppings. Most of the tracks were pointing north, straight for the neighbor's small sweet corn patch and the few ears left just for the deer. Nothing stirred on that night ... until ... the woodland's serenity was broken by the chilling hoot of a great horned owl.

The bird was quickly answered by another great horned, and soon both birds exchanged a series of nearly identical hoots with each other.

I paused to listen and wonder about the meaning of their curious communiqué. Were they simply greeting each other after slumbering the day away? Were they mates? Nest mates? Or were they strangers to each other? Was one great horned owl informing the other great horn that this neck of the woods was its own? Was it time to go hunting?

Whatever the case was, I did know at least this: Creatures of the woods -- be they small rodents, rabbits or hares, or otherwise listless animals of both feather and fur -- had best beware of those vocal, soon-to-be silent and deadly predators of the nighttime forest. Owls were on the hunt.

Most owls are nocturnal, and all are birds of prey. Some, like short-eared owls, are daytime and twilight hunters. But for most species, dusk and night is the time for a shift-change at the raptor time clock. Replacing eagles, hawks and falcons as top avian diurnal predators, owls are true masters of darkness and come equipped with adaptations unmatched in any other predatory species of bird.

One of my favorite Minnesota owls is the barred owl. This owl, which is closely related to the great gray owl, is smaller than both the great horned and great gray. Its head has no feather-tufts and its underside is streaked with a barring pattern.

Most distinctive of all is the barred owls' familiar call: "hoo, hoo, too-HOO; hoo, hoo, too-HOO, ooo", or, best known by human admirers as: "Who cooks for-you? Who, cooks, for-you, all?" No other owl gives a hoot like this owl can hoot.

Like most owls, barred owls hunt during the night hours. And like all other owls, their vision is extraordinarily acute. On exceptionally dark nights, an owl's pupils are at its largest, which in turn allows the maximum amount of light to enter into its eyes. Special light-sensitive cells contribute to an owl's amazing ability to see in the dark.

But unlike other animals, owls' eyes are immobile and are fixed solidly in their eye sockets, unable to move up, down, sideways or around. Owls cannot move their eyes at all. However, they can move their heads nearly completely around, about 270 degrees! This is possible because of an owl's long neck and abundant neck vertebrae. For comparison, we have just seven vertebrae to the owl's 14.

While owls certainly rely on vision to locate prey, sensitive hearing and pronounced facial disks help to pinpoint prey location and to reflect sounds of scurrying animals many dozens of feet away too. As well, soft wing-feathers provide silent flight in order to fly and capture prey undetected while long and sharp talons on each foot serve as deadly weapons to hold prey securely once captured.

Some species, like great gray, northern hawk and snowy owls, occur more frequently during some years than at other times. For example, during the winter of 2011-12, because of a shortage of food in their Canadian habitats, snowy owls were observed farther south in the Red River Valley. Other owls, such as barn owls and burrowing owls, have a limited range in Minnesota.

Minnesota's owls hunt for prey from as small as insects and frogs to as large as hares and skunks. Small prey, like mice and voles, are swallowed whole -- bones and all. Owls consume larger prey in chunks they tear from carcasses by using their hooked beaks.

And since an owl's digestive system cannot process bones and fur, these parts are regurgitated in scat-like pellet form that are often found beneath favorite roosting sites and nest trees in the forest. These "owl pellets" provide the interested observer a special opportunity to learn not only what the bird was feeding on, but also a clue where it may live.

The great horned owls I listened to on that icy December night, though just as much owl as the barred owl, are not friends to any of the species owl cousins. Barred owls share the same territory and habitat as do great horned owls do, and so they must maintain watchful eyes and listening ears for the sight or hoot of the larger great horn. Great horned owls are the barred owl's enemy. Many an unwary barred owl has become dinner for the cunning great horned.

And so it is; that these birds of prey -- owls -- alight among the branches within the forested canopies surveying dark shadows for prey, signaling to us with their resounding calls that they most assuredly exist, though we rarely view them in full, daylight splendor, is but another reason to give a hoot as we get out and enjoy the great outdoors.

BLANE KLEMEK is a Minnesota DNR wildlife manager. He can be reached at bklemek@yahoo.com.